Power source converter

ABSTRACT

A power source converter apparatus that is the structural and functional  ivalent of a typical internally stored battery, such as a lithium organic cell. The converter has a shape and size that conforms to that of the battery being replaced. The converter includes a pair of output terminals that can make electrical contact with appropriate elements in the unit in the same manner as did the battery it replaces and a pair of input terminals accessible to the exterior of the unit for connection to an external power source. Internally of the converter body, there is mounted an electronic circuit to be used as a power conditioner and a voltage regulator for performing the proper DC-to-DC voltage conversion to ensure the necessary voltage at the output terminals. A threaded cap is fixed to the converter for use in covering the opening in the battery housing.

The invention described herein may be manufactured, used, and licensedby or for the Government for governmental purposes without the paymentto me of any royalty thereon.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power source converter apparatuswhich directly replaces an internally stored battery of an electronicunit so that the unit may be operated from a different, external powersource such as a vehicle battery.

2. Description of the Prior Art

In the field of electronics, there are numerous battery powered unitsthat can operate on only one type of internally stored battery. Therequired battery will usually have a specific size, configuration,voltage, etc. In some cases, the type of battery required to operate aspecific unit imposes certain restrictions on the overall use andoperation of the unit. For example, in military equipment, one populartype of internally stored DC power source is the lithium organic cell, abattery that often imposes severe limitations on the use of the units inwhich they are placed. More specifically, the Litton DCT unit, apopular, hand-held digital communications terminal, is normally operatedwith a 9-volt lithium organic cell. Military restrictions prevent theuse of the Litton DCT unit in certain enclosed areas because of thepotential hazard to personnel in the event of improper handling.Consequently, in the past, the Litton DCT units and other like deviceswere normally stored or used only outside of non-authorized areas. Inaddition to the obvious inconvenience created, there are times whenspecific important tasks involving the inputting of critical data cannotbe performed without gaining access to the non-authorized areas.

Although those concerned with the use or development of suchbattery-operated units as the Litton DCT unit have long recognized theproblems often imposed by the use of certain internally storedbatteries, no practical solution has yet been devised.

SUMMARY OF THE INVENTION

The general purpose of this invention is to provide a power sourceconverter that can be used in a unit to replace an internally storedbattery so that the unit may be operated safely from an externalbattery. To attain this, the present invention employs a power sourceconverter apparatus that is the structural and functional equivalent ofa typical internally stored battery, such as a lithium organic cell.

More specifically, the converter of the present invention has a shapeand size that conforms to that of the battery being replaced. Theconverter also includes a pair of output terminals that can makeelectrical contact with appropriate elements in the unit in the samemanner as did the battery it replaces. The converter further includesinput terminals accessible to the exterior of the unit for connection toan external power source. Internally of the converter body, there ismounted an electronic circuit to be used as a power conditioner and avoltage regulator for performing the proper DC-to-DC voltage conversionto ensure the necessary voltage at the output terminals. The majorportion of the converter body is made of a thermally conductivematerial, such as aluminum, to act as a heat sink for conducting heataway from the converter circuit which has heat generating elementstherein.

It is, therefore, an object of the present invention to provide a DCpower source converter that may be used as a replacement for aninternally stored battery.

Another object is to provide a DC power converter that is the functionaland physical equivalent of an existing DC power source, such as alithium organic battery configured to power a Litton DCT.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings in which like referencenumerals designate like parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the preferred embodiment.

FIG. 2 is a top plan view of a portion of the device shown in FIG. 1.

FIG. 3 is a sectional view of a typical battery housing.

FIG. 4 is an end view of the device shown in FIG. 2.

FIG. 5 is an end view of a portion of the device shown in FIG. 1.

FIG. 6 is an end view showing details of still another portion of thedevice shown in FIG. 1.

FIG. 7 is a pictorial view of portions of the device shown in FIG. 1.

FIG. 8 is a schematic circuit diagram of the preferred circuit to beused with the device shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is shown a power source converter11 having a body 13, with a contactor plate 15 and an end cap 17 mountedat opposite ends thereof. The body 13 is generally dumbell shaped withenlarged portions 14, 16 separated by a flat platform 23 to form a pairof chambers 19, 21. A circuit board assembly 25 is mounted in chamber 19and is fixed to one side of platform 23 by bolts 27 that pass throughassembly 25 and openings 18, 24 in platform 23. A pair of insulatingspacers 31, 33 are placed between assembly 25 and platform 23. On theother side of platform 23 in chamber 21, a circuit element 35 (voltageregulator) is fixed by one of a pair of nuts 36 that secure bolts 27.Circuit element 35 is insulated from body 13 by an insulating washer 37.A plurality of electrical conductors 39 pass through opening 22 inplatform 23 from circuit element 35 to assembly 25. Element 35, assembly25 and conductors 39 are part of a circuit 71 that will be described ingreater detail below with respect to FIG. 8.

Axial through-holes 41, 43 extend axially through portions 14, 16,respectively, from either end thereof to chamber 19. A pair ofelectrical conductors 45 pass through hole 41 to make a properelectrical connection between assembly 25 and a pair of terminals 47, 48on contactor plate 15.

Contactor plate 15 is preferably fabricated by depositing conductivematerial, such as copper, on one side of a typical printed circuit boardand etching the inner terminal 47 and outer annular terminal 48. Innerterminal 47 includes an alignment bead 49 that cooperates with a contactspring 88 (FIG. 3) located inside the battery housing 87. The bead 49will prevent the contact spring 88 from sliding off the terminal 47. Thecircuit board of contactor plate 15 may be assembled on body 13 by firstattaching conductors 45 to terminals 47, 48 and then cementing the backsurface of plate 15 to the body 13 with an epoxy bond or similarsubstance.

Four conductors 46 extend through hole 43 from assembly 25 to aconventional female connector 51 having a threaded portion 53. Connector51 may be a commercial BNC connector. The end cap 17, shown in sectionin FIG. 1, is cup-shaped with inner threads 52 and includes a centralopening 55 for receiving the threaded portion 53 and apertures 63 forbolts 61. The cap 17, except for the openings therein, is generallyconfigured to the shape of the battery housing cap 86 that is threadedonto battery housing 87 (FIG. 3).

A nut 57 is threaded onto portion 53 for fixing connector 51 to cap 17.Two of the conductors 46 are soldered or otherwise joined to theterminals of female connector 51. Two of the conductors 46 are attachedto a light emitting diode (LED) 81 bonded to cap 17 at an opening 82.The hole 43 has an enlarged portion 59 for providing proper clearancefor receiving connector 53, the nut 57, LED 81 and the attachedconductors 46 when cap 17 is assembled onto portion 16 of body 13. Cap17 is fixed to body 13 by a pair of bolts 61 and washers via apertures63 in the cap 17 and threaded holes 65 in body 13. A rubber 0-ring 67 isfit into the space between the inner threaded portion 52 and the outersurface of portion 16. The housing 87 for holding the converter 11 hasan outer threaded portion 83 that fits between the cap 17 and the outersurface of portion 16 to mate with the threads 52. When the cap 17 isthreaded onto the portion 83, the portion 83 will press against 0-ring67 thereby forming a seal.

A pair of identically shaped, thin-walled semi-cylindrical shell covers68, 69 have the edges thereof supported by a pair of annular shoulders64, 66. Small screws 62 pass through cut-outs 54 on covers 68, 69 intothe threaded holes 56 on shoulders 64, 66.

The structure, including the covers 68, 69, and plate 15 is the physicalequivalent of the battery being replaced. The terminals 47, 48 will makeelectrical contact with the corresponding contacts 88, 89 in the housing87 in the same manner as do the battery terminals (not shown). Theconnector 51 is accessible to the exterior of housing 87 for connectionto an external DC power source between 9 and 37 volts (not shown) by aconventional cable having a male connector.

With particular reference to FIG. 8 where circuit 71 is shown in detail,the connector 51 includes input terminals 72, 73 for connection to thenegative and positive terminals, respectively, of the external DC powersource. Capacitors C1 and C2, inductor L1 and transformer T suppresstransients that may occur at the input terminals 72, 73. A pair of coilsform the transformer T that has one end of the coils connected to eitherside of the capacitor C2 and the other end of the coils connected toeither side of a capacitor C3. A commercial voltage regulator 35 has avoltage input terminal Vin connected to the node between one side oftransformer T and capacitor C3. The voltage output terminal Vout ofregulator 35 is connected to the outer terminal 48 on plate 15 (FIG. 5).A voltage divider circuit, formed by resistors R2 and potentiometer R1,is connected between the output terminal Vout and the other node betweentransformer T and capacitor C3. The moveable contact on potentiometer R1is connected to regulator 35. An output capacitor C4 is connected acrossthe voltage divider (R1 and R2). A series-connected resistor R3 andlight emitting diode 81 are connected in parallel across capacitor C4and terminals 48, 49. The voltage regulator 35 is preferably anintegrated circuit that will sense changes in voltage across the voltagedivider formed by resistors R1 and R2 and in response will automaticallychange its resistance so as to maintain a constant DC voltage at theoutput terminals 48, 49. The output voltage at terminal Vout isinitially calibrated by adjusting potentiometer R1 and then fixing it inplace by depositing a bonding agent thereon. The diode 81 will, ofcourse, act as an indicator device by emitting light only when there issufficient voltage present at the terminals 48, 49.

The circuit of FIG. 8 has the following preferred values for the variouscomponents thereof when used in a converter 11 as a substitute for thelithium organic cell #305226.

    ______________________________________                                                  ELEMENT  VALUE OR PART NO.                                          ______________________________________                                        Capacitor   C1         .05     microfarad                                     Capacitor   C2         100     microfarads                                    Capacitor   C3         .1      microfarad                                     Capacitor   C4         1       microfarad                                     Inductor    L          100     microhenrys                                    Resistor    R1         5       kilo-ohms                                      Resistor    R2         240     ohms                                           Resistor    R3         330     ohms                                           Voltage Regulator                                                                         35         LM317 (1.5 AMPS)                                       ______________________________________                                    

The transformer T is preferably wound with 22 gauge copper wire on asteel, 1/8 inch rod rolled into a toroid with a 3/8 inch diameter. Thewindings of transformer T may be wound of opposite sides of the toroid.

Typical values for the dimensions a-r are listed below. These valuesrepresent the preferred values for the converter 11 when used as asubstitute for the lithium organic cell #305226.

    ______________________________________                                        DIMENSION     SIZE IN INCHES                                                  ______________________________________                                        a             11/2                                                            b             1/4                                                             c             5/8                                                             d             3/8                                                             e             2                                                               f             2                                                               g             3 3/16                                                          h             17/8                                                            i             1/16                                                            j             3/8                                                             k             3/8                                                             1             11/2                                                            m             1/4                                                             n             3/8                                                             p             21/4- q 3/16                                                    r             3/4                                                             ______________________________________                                    

It should be understood, of course, that the foregoing disclosurerelates to only a preferred embodiment of the invention and thatnumerous modifications or alterations may be made therein withoutdeparting from the spirit and the scope of the invention as set forth inthe appended claims.

The foregoing disclosure and drawings are merely illustrative of theprinciples of this invention and are not to be interpreted in a limitingsense. It is to be understood that the invention should not be limitedto the exact details of construction shown and described because obviousmodifications will occur to a person skilled in the art.

What is claimed is:
 1. A DC power source converter comprising:anelongated body having opposed first and second ends, and a chamberformed therein; a first pair of electrical terminals mounted on thefirst end; a second pair of electrical terminals mounted on the secondend; and DC-to-DC converter means mounted in said chamber and connectedbetween said first and second pair of terminals for converting DC powerapplied to the first pair of terminals to a predetermined DC voltage atthe second pair of terminals.
 2. The converter of claim 1 wherein thebody is generally cylindrical in shape.
 3. The converter of claim 2wherein first and second longitudinal bores extend through said bodyfrom said chamber to said first and second ends, respectively, andconductors extend through the bores to connect said DC-to-DC convertermeans to said terminals.
 4. The converter of claim 2 wherein said firstend includes a cover means for enclosing a housing in which saidconverter is to be mounted, and wherein said first pair of electricalterminals are mounted on said cover means.
 5. The converter of claim 4wherein said cover means includes a threaded cap.
 6. The converter ofclaim 5 further including a DC voltage indicator mounted on said cap andconnected to said DC-to-DC converter means.
 7. The converter of claim 6wherein said DC voltage indicator is a light emitting diode.
 8. Theconverter of claim 1 further including a housing in which said body ismounted.
 9. The converter of claim 8 wherein said first end includes acover means for enclosing said housing and wherein said first pair ofelectrical terminals are mounted on said cover means.
 10. The converterof claim 9 wherein said second pair of terminals includes an annularterminal surrounding a central terminal.
 11. The converter of claim 10wherein said cover means includes a threaded cap coupled to an open endof said housing.
 12. The converter of claim 11 further including a DCvoltage indicator mounted on said cap and connected to said DC-to-DCconverter means.